I currently use many Atom S3 Lite which only have 320KB of RAM or so (and 8 MB Flash Memory).

The Core S3 has 16MB Flash and 8MB of PSRAM according to https://docs.m5stack.com/en/core/CoreS3.
But it is also VERY expensive at 50+ EUR and has many things I don't really need (Capacitive LCD, Battery, MicroSD, Speaker and MIC for one) since I mainly play with CANbus/RS485/WiFi/BLE.

Is there a low-cost version of the ESP32-S3, "just" with the extra PSRAM?

I could not find one at least ...